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<html lang="en">
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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    
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</html>
<script>
    // var str='112'
    // alert(Number(str))
    // var s='来了，他们来了'
    // alert(s)
    // var b='我看到你们了';
    // console.log(Boolean(b))
    // console.log(typeof(b));
    // var c='9.9'
    // console.log(parseFloat(c));
    var a=NaN
    console.log(a);
    console.log(typeof(a));
    console.log(10 % 9);
    
    
    
</script>